The present invention relates to an electrically driven gas flow control apparatus in a gas appliance such as, for example, a gas cooking range.
The conventional gas flow control apparatus of a kind having this type of function employs a geared motor for controlling the flow of gas. However, the conventional gas flow control apparatus employing the geared motor has problems in that it is difficult to accomplish even a slight control, that is, to control the gas flow in a slight quantity. In addition, with the conventional gas flow control apparatus, the flow control characteristic is such that the gas power can be adjustable stepwise, the number of stepwise adjustable positions available being limited. Not only is the number of the available stepwise adjustable positions limited, but also the speed at which the gas power can be adjusted is not controllable, accompanied by such a problem that if the gas power is abruptly adjusted down to a low flame position, the gas flame tends to be extinguished.
The present invention has been devised to substantially eliminate the above discussed problems inherent in the prior art gas flow control apparatus and is intended to provide an improved gas flow control apparatus capable of providing a white-gloved fine adjustment of the gas power. Disclosure of the Invention
To this end, the present invention provides a gas flow control apparatus comprising a gas flow control unit having a gas flow control function of adjusting the flow of gas and a stopping function of selectively initiating and interrupting the supply of gas, a stepping motor for driving the gas flow control unit and a drive control unit for controlling the stepping motor. The gas flow can be adjusted according to the number of pulses applied to the stepping motor, thereby to accomplish the white-gloved fine adjustment.
The gas flow control apparatus is preferably of a structure wherein a variable flow control in which the flow of gas is varied stepwise according to the number of pulses applied to the stepping motor, a flat flow control in which the flow of gas is not varied and a gas interrupting control are performed. This feature makes it possible to allow the gas flow to adjusted finely and in one of a plurality of stepwise gas flows according to the number of pulses applied to the stepping motor.
The gas flow control unit may comprises a slide shutter having an adjusting portion for the flow of gas; a cock body accommodating the slide shutter; a flow control plate having a gas flow adjusting portion; and a drive connecting unit for connecting the slide shutter to the stepping motor, whereby a relative position between the adjusting portion of the slide shutter and the gas flow adjusting portion of the flow control plate is varied by a pulsed drive of the stepping motor to thereby accomplish a gas flow adjustment and interruption. In such case, since a linear sliding motion of the slide shutter suffices, the driving torque required can be reduced as compared with a rotary shutter and, also, the gas interrupting capability when the slide shutter is moved to a closed position can be improved.
The gas flow control apparatus may further comprise a position detecting means for detecting a gas flow control position and wherein the drive control unit includes a position determining means for determining the gas flow control position based on at least a signal from the position detecting means. Even this feature makes it possible to accomplish the gas flow control and interruption.
The drive control unit may be so designed as to ascertain a position based on both the number of pulses applied to the stepping motor to drive the latter and a position determining signal from the position detecting means. According to this feature, since the position of the slide shutter according to the number of pulses applied to the stepping motor and that according to the output from the position detecting means are doubly managed, the accuracy of the gas flow control can be increased to assuredly interrupt the supply of gas to ensure the safety factor.
Preferably, the drive control unit is operable to add a predetermined number of pulses to be applied to the stepping motor to drive the latter to a position determining output of the position detecting means to define a predetermined gas power position, so that a highly accurate gas flow control and interruption can be performed in a simple manner.
In a different aspect of the present invention, there is provided a gas flow control apparatus which comprises a gas flow control unit having a gas flow adjusting capability and a gas closing capability of selectively opening and closing a gas; a stepping motor for driving the gas flow control unit; and a drive control unit for controlling the stepping motor. The drive control unit includes a burner drive determining unit for adjusting a speed of a drive unit from a flow control position of the flow control unit. In this embodiment, at least when a gas flow control valve of the flow control unit is positioned at a position adjacent the minimum flow position, the drive speed is reduced and, therefore, any possible abrupt extinction resulting from an abrupt adjustment to the low flame position can be avoided, allowing the gas flow control apparatus to gain reliability from the user. Also, a red-hot phenomenon which would otherwise result from an abrupt adjustment to the high flame potion can also be avoided and, therefor, no snoot will deposit on a pan, allowing the gas flow control apparatus to gain reliability from the user.
Preferably, the burner drive determining unit is operable to reduce the drive speed when the drive unit is moved to at least a position adjacent a minimum flow position of the flow control unit. In this case, since the gas flow adjusting unit is actuated at a high speed other than at the minimum flow position during the extinction, the extinction can take place quickly. In addition, since the length of time during which the drive unit is driven is reduced, the electricity saving can be achieved and the user can be ensured as to the reliability in operation.
In a further aspect of the present invention, there is provided a gas flow control apparatus which comprises a gas flow control unit having a gas flow adjusting capability and a gas closing capability of selectively opening and closing a gas; a stepping motor for driving the gas flow control unit; and a drive control unit for controlling the stepping motor. The drive control unit is operable to perform a variable speed control by determining a correlation with a flow control position of the flow control unit without an electric power being supplied for a predetermined cycle while the frequency of power supply pulses is fixed, to thereby vary a drive speed. According to this embodiment, the speed can be varied depending on the combustion power and also on the purpose of operation such as, for example, ignition, extinction and a gas power adjustment.
In one aspect of the present invention, there is also provided a gas flow control apparatus which comprises a gas flow control unit having a gas flow adjusting capability and a gas closing capability of selectively opening and closing a gas; a stepping motor for driving the gas flow control unit; and a drive control unit for controlling the stepping motor. The drive control unit includes a voltage determining means, an electricity saving means for performing a duty control according to a level of voltage by fixing the frequency of pulses to be applied to the drive unit according to a level of a power source voltage, a position determining means for determining a correlation with a flow control position of the flow control unit, and a motor speed control means for supplying no electric power for a predetermined cycle by fixing the frequency of the power supply pulses; whereby an electric power to be supplied is leveled by converting the level of the power source voltage into a level of a duty ratio. Accordingly, the level of the power source voltage can be converted into the level of the duty ratio to thereby level the electric power to be supplied.
The drive control unit may be of a design capable of selecting one of a plurality of combinations in which no electric power is supplied for each cycle for speed control so that the stepping motor can have its speed controllable as desired.
According to a still different aspect of the present invention, there is provided a gas flow control apparatus which comprises a gas flow control unit having a gas flow adjusting capability and a gas closing capability of selectively opening and closing a gas; a stepping motor for driving the gas flow control unit; and a drive control unit for controlling the stepping motor. The drive control unit may include a voltage determining means for a drive control battery power source and an electricity saving determination means for leveling an electric supply power. This is particularly advantageous in that even when variation takes place in the power source voltage, the electric supply power can be leveled to accomplish the energy saving feature.
The electricity saving determining means may be so designed as to vary a frequency of the pulses to be applied from the power source to the drive unit and is operable to level the electric supply power by converting a level of the power source into a level of the frequency. This feature makes it possible to accomplish the gas power adjustment with the constant torque of the stepping motor and, therefore, even at a low voltage, an abnormal operation will hardly occur. In other words, the lifetime of the battery constituting the power source can be extended.
Alternatively, the electricity saving determining means may be so designed as to perform a duty control according to a level of voltage by fixing the frequency of the pulses to be applied to the drive unit based on the power source voltage and is operable to level the electric supply power by converting the level of the power source voltage into a level of a duty ratio. This feature makes it possible to provide a gas appliance in which even when the voltage varies (the voltage of the battery decreases), the gas power can be adjusted at a constant speed.
A still further aspect of the present invention provides a gas flow control apparatus which comprises a gas flow control unit having a gas flow adjusting capability and a gas closing capability of selectively opening and closing a gas; a stepping motor for driving the gas flow control unit; and a drive control unit for controlling the stepping motor. The drive control unit is operable to measure a frequency of drive of the drive unit and to increase a torque of the drive unit when the measurement is performed for the first time. According to this structure, the gas flow control apparatus can be operated with the power source saved to extend the lifetime of the battery and with the stepping motor operated with high torque.
Furthermore, according to a still further aspect of the present invention, there is provided a gas flow control apparatus which comprises a gas flow control unit having a gas flow adjusting capability and a gas closing capability of selectively opening and closing a gas; a stepping motor for driving the gas flow control unit; a position detecting means for detecting a flow control position of the gas flow control unit and a gas interrupted condition; and a drive control unit for driving the stepping motor and for determining a position with reference to a signal from the position detecting means. The drive control unit may include a position determining means for controlling the gas flow control unit to a predetermined position by means of the number of pulses to be applied to the stepping motor to thereby correct a movement of a pulse drive at the predetermined position of the position detecting means. According to this construction, even though variations occur in component parts of the gas flow control unit and/or the stepping motor, the position can be corrected by a position detector and, therefore, the component parts may not be severely managed as to their precision and an accurate predetermined flow can be secured.
The drive control unit may also include a position determining means for increasing an accuracy of a gas flow adjustment by counting the number of pulses necessary for the position detecting means to return to the predetermined position by accomplishing a reverse rotation after a predetermined number of pulses has been supplied to the stepping motor, determining an error peculiar to the apparatus by determining a difference between the numbers of pulses during reciprocating motions, and by adding or subtracting the peculiar error of the apparatus to or from the number of pulses at a desired position in the event that a direction of rotation differs. In this embodiment, the error peculiar to the apparatus is determined in terms of the difference between the number of pulses during movement in one direction and that during movement in the opposite direction. When the direction of rotation differs, this error is added or subtracted to or from the number of pulses required to move towards the desired position to thereby increase the gas flow adjusting accuracy.
Preferably, the drive control unit may detect the error peculiar to the apparatus at the time of igniting operation, so that detection of the error need not be performed each time the igniting operation is performed. It is to be noted that the error may be stored in the drive control unit.
According to an alternative aspect of the present invention, there is provided a gas flow control apparatus which comprises a gas flow control unit having a gas flow adjusting capability and a gas closing capability of selectively opening and closing a gas; a stepping motor for driving the gas flow control unit; a position detecting means for detecting a flow control position of the gas flow control unit and a gas interrupted condition; and a drive control unit for driving the stepping motor and for determining a position based on an output from the position determining means. The drive control unit is operable to supply an electric power by increasing an electric supply power to increase a torque of the stepping motor in the event that the position determining means fails to reach the predetermined position even though a predetermined number of pulses is supplied to the stepping motor.
The drive control unit may be so designed as to supply the electric power by increasing the electric supply power to increase the torque of the stepping motor at a first time of abnormality in the event that the position determining means fails to reach the predetermined position even though the predetermined number of pulses is supplied to the stepping motor, but causing the position determining means to reach the predetermined position by effecting an operation reverse to a predetermined position direction and then reversing in a direction back to the predetermined position in the event that the position determining means fails to reach the predetermined position even though the increased electric power is supplied.
Preferably, the drive control unit is of a structure effective to accomplish a supply power control under a duty control by fixing a frequency of applied pulses and to increase the electric supply power by increasing a duty ratio in order to increase a torque of the stepping motor. Also, the drive control unit may be of a structure operable to perform the supply power control under a level control of the frequency by rendering the frequency of the applied pulses to be variable and to increase the electric supply power by lowering the frequency in order to increase the torque of the stepping motor.
The present invention also provides a gas appliance utilizing a gas flow control apparatus of the structure described hereinabove. This gas appliance comprises a control panel for issuing an instruction to the drive control unit of the flow control apparatus and including a gas control key and a gas power adjusting key and wherein the drive unit of the flow control unit has a plurality of stepwise variable flow characteristics each having a linearly variable flow portion, in which the gas flow varies according to pulses for driving the drive unit, and a flat portion in which the gas flow does not vary, and wherein the drive control unit is of a structure wherein depending on contents of a signal input from the gas power adjusting key a decision is made to determine whether a stepwise gas power change or a linear gas power change is desired and a selection instruction of one of the linear gas power change and the stepwise gas power change is issued.
In this gas appliance, the drive control unit may include a motor speed control means for changing a drive speed of the drive unit and wherein depending on the contents of the signal input from the gas power adjusting key a decision is made to determine whether the stepwise gas power change or the linear gas power change is desired and the selection instruction of one of the linear gas power change and the stepwise gas power change is issued and, when the linear gas power change is selected, a gas power adjusting speed is slowed as compared with the stepwise gas power change.
When a period during which the gas power adjusting key is depressed is shorter than a predetermined value, a gas power may be switched stepwise, but when the period during which the gas power adjusting key is depressed is longer than the predetermined value, the gas power is changed linearly. Moreover, the drive control unit may include a key input trouble determining means and wherein a length of time during which a trouble of the gas power adjusting key is determined is set to be longer than a length of time during which a gas power switching selection is carried out.
Preferably, the drive control unit includes a position detecting means for detecting a position of a flow control unit and wherein when the gas power is changed linearly, a maximum gas power and a minimum gas power causes a display means to be switched on according to the position of the position detecting means, but a display position is changed in case of a medium gas power according to a number of pulses. Alternatively, the drive control unit may include a position detecting means for detecting a position of a flow control unit and wherein when the gas power is changed linearly, a maximum gas power and a minimum gas power causes a display means to be switched on according to the position of the position detecting means, but when the gas power is changed stepwise, a specified display is switched on and displays at respective above and low positions are switched on or blinked in case of a medium gas power according to a number of pulses.
The comprises a plurality of gas burners and wherein when some of the gas burners are activated, the drive control unit drives in succession stepping motors associated with such some of the gas burners without them being activated simultaneously. In such case, the drive control unit may be so designed as to drive the stepping motors by giving the highest priority to a gas extinguishing operation, the second highest priority to a gas igniting operation, the third priority to a manual gas power adjusting operation and the fourth priority to an automatic gas power adjusting operation.